# icggThe Kinetic Theory of Matter

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```					        Chapter 10: The Kinetic Theory of Matter

States of matter
Solid           Rigid matter with a definite shape and
volume
 Particles are close together
Liquid          Flowing matter with a definite volume but
no definite shape
 Takes the shape of its container
 Particles are farther apart than a solid
Gas             Flowing, compressible matter with no
definite volume or shape
 Takes the volume and shape of its container
 Particles are farther apart than a liquid
Kinetic theory of matter
 Kinetic theory: particles of all matter are in constant,
random motion
o Particles have kinetic energy (energy of motion)
 Brownian motion: constant, random motion of tiny chunks
of matter
 Ideal gas: a gas that follows the kinetic theory
o Gas particles are in constant random motion, never
stick to each other, and bounce off the walls of
their container
o When gas particles
bounce off the walls of
their container, they
exert pressure on the
walls of the container
o Pressure: force acting      Gas
on a unit area of a
surface
 Liquids: Particles stick to each
other (fixed volume) but
particles slide past each other         Liquid
(no fixed shape)
 Solids: Particles are in fixed
positions (fixed volume and
shape)
o Crystal lattice: the
fixed arrangement of
particles which is repeated
throughout a solid
Solid
Phase Diagrams: Graph that shows the phase of one substance at
different pressures and temperatures

Critical Point: Temperature and pressure at which a liquid and its vapor
become identical

Triple Point: Temperature and pressure at which solid, liquid, and gas
phases coexist

1. What is the state of water at 2 atm and 50 ?
Liquid

2. What phase change will occur if the temperature is lowered from
80C to -5C at 1 atm?
Liquid to Solid

3. You have ice at -10C and 1 atm. What could you do in order cause
the ice to sublime?
Lower the pressure below 0.0060atm
Materials that can’t be classified as solid, liquid, or gas

Liquid crystals
 A material that loses its rigid organization in only one or
two dimensions when it melts
 Particles are still lined up in at least 1 direction in the liquid
state

   LCDs used in monitors, calculators, etc are liquid crystal
displays

Amorphous materials
 Matter with a haphazard, disjointed, and incomplete
crystal lattice
 Think of it like a solid that can take the shape of its
container
 Peanut butter, candles, cotton candy

Plasma
 Plasma: ionized gas (atoms have been separated into
positive and negative pieces)
 Form at very high temperatures
 Fluorescent light bulbs, stars
Mixtures involving different phases:

Suspension                   Colloid                  Solution

1 nanometer (nm) =
1x10-9 m
Suspension
 Heterogeneous mixture containing large particles
 Particles are so large they will settle out over time and can be filtered out
 Categorized as a liquid
 Examples: sandy water, muddy water, house paint

Colloid
 Heterogeneous mixture containing medium particles
 Categorized according to the phase of the particle and medium
 Ex: Milk-liquid particles in liquid medium
 Ex: Mayonnaise-liquid particles in liquid medium
 Ex: Marshmallow-gas particles in solid medium
 Ex: Smoke-solid particles in gas medium

Solution
 Homogeneous mixture containing very small particles
 Categorized according to the phase of the medium
 Ex: Gasoline-liquid solution
 Ex: Salt water-liquid solution
 Ex: Air-gas solution
 Ex: Steel-solid solution
Temperature and Particle Motion
 Temperature: Measure of the average kinetic energy of
the particles in a material

High temperature
High kinetic energy

Low temperature
Low kinetic energy

   Kelvin scale: Temperature scale that relates
temperature to the average kinetic energy in a material
o O Kelvins (O K) = Absolute zero = lowest possible
temp. = particles have no kinetic energy

Temperature conversions
TK = TC + 273              TK = Temp. in Kelvin

TC = TK – 273              TC = Temp. in Celsius

Diffusion
 Process by which particles of matter fill a space
because of random motion
 Ex. Food coloring spreads out when a drop is
placed in a glass of water
 Ex. Particles of hot coffee travel in a gas to your
nose as you smell the coffee
Changing state
Melting                     Evaporation
 Solid                      Liquid                  Gas
Freezing                   Condensation

Sublimation

Evaporation and condensation
 Water in a closed container will only evaporate until the
water is evaporating and condensing at the same rate
 Then the vapor (gas) is in equilibrium with the liquid
 Vapor pressure: The pressure of a gas in equilibrium with
its liquid

 High vapor pressure = liquid evaporates quickly (alcohol)
 Low vapor pressure = liquid evaporates slowly (water)
 Boiling point: temperature of a liquid when its vapor
pressure equals the atmospheric pressure
 Heat of vaporization: Energy needed to vaporize
(evaporate) 1 kg of a liquid at its normal boiling point
   Joule: unit used to measure energy

Melting and freezing
 Melting point: temperature of the solid when its crystal
lattice begins to fall apart
 Freezing point: temperature of a liquid when it begins to
form a crystal lattice and becomes a solid
 Heat of fusion: Energy given off by 1 kg of a substance
as it freezes (energy needed to melt 1 kg of a substance)

Vocabulary

Absolute zero                    Joule
Amorphous material               Kelvin
Boiling point                    Kelvin scale
Brownian motion                  Kinetic theory
Condensation                     Liquid
Crystal lattice                  Liquid crystal
Diffusion                        Melting point
Evaporation                      Plasma
Freezing point                   Pressure
Gas                              Solid
Heat of fusion                   Sublimation
Heat of vaporization             Temperature
Ideal gas                        Vapor pressure

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